Understanding the control of ingestion is of major importance to the health of animals and humans. In order to understand the controls of ingestive behavior, it is necessary 1) to appreciate the metabolic signals which are monitored in the interest of increasing or decreasing food and fluid intake 2) to identify the receptors which monitor these signals and 3) to determine the role of a particular set of receptors in the day to day control of ingestion. Work outlined in this application proposes to use a novel glucose analogue, 5-thioglucose, in conjunction with other new approaches to locate the glucoreceptors which mediate feeding in response to glucoprivation. The application also proposes respirometric and behavioral examination of feeding elicited by pharmacological agents which cause glucoprivation. The proposed experiments will also investigate a brainstem chemoreceptor area (the area postrema) which seems to be involved in the adjustment of intake of highly palatable substances. We have recently found that lesions of this previously ignored area cause dramatic increases in the intake of sweet and salty substances without altering ingestion of the apparently bland laboratory diet. The proposed experiments involve 1) further testing of taste responsiveness in area postrema-lesioned rats 2) using systemic and intracranial infusion techniques to determine area postrema sensitivity to humoral signals which alter ingestive behavior and 3) studying the fine grain of ingestive behavior of lesioned rats to determine how loss of this region influences spontaneously initiated ingestion.